1. Field of the Invention
This invention relates to hand held hot air hair dryers, and more particularly to improvements therein whereby hot air flow rate is mechanically adjusted without any substantial change in the electrical load to the motor driving the fan therein.
2. Description of the Prior Art
A conventional hand held hot air hair dryer usually comprises an outer housing having an opening in the sides thereof for entrance of air, and a nozzle mouth for exit of hot air, an inner housing disposed in the outer housing and also having a mouth for the exit of blown air and side openings conforming to the side openings in the outer housing for entry of air, a fan disposed within the inner housing and driven by a motor, and heater means disposed toward the mouth of the outer housing for heating the blow air prior to exit from the nozzle mouth. A first electrical switch is used for varying the power supplied to the heater, and a second electrical switch is used for varying the speed of the motor to thereby vary the velocity of the air flow exiting the nozzle mouth.
A particularly difficult problem arises in that changing the air speed by changing the motor speed places substantial load variations on the motor and greatly reduces the efficiency and life of the hair dryer.